Supervisory signal for telephone-switchboards.



PATENTED APR. 17, 1906.

F R. MoBERTY. SUPERVISORY SIGNAL FOR TELEPHONE SWITOHBOARDS.

APPLICATION FILED JAN. 24, 1902.

am m 7 0 fl U V W 3 h M f g UNITED STATES PATENT OFFICE;

FRANK R. MCBERT or EVANSTON, ILLINo s, 'AssIGNoR TO WESTERN ELECTRIC COMPANY, or oHIoAeo, ILLINoIs, A, CORPORATION-OF ILLINOIS.

SUPERVISORY SIGNAL Fon TELEPHONE-:SWITCHBOARDS.

No. 817,867. Specification r Letters .Patent. Patented. April 1'1, 19Q6.

Application filed January 24,1902; Serial No. 91,031- I v To all whom it may concern/i I Should the resistances of thelarnps vary after Be it known that I, FRANK R. MoBERTY, a some'period of use,which frequentlyghappens, citizen of the United States, residing at Evansor if the potential of the battery e varied,

ton, in the county of Cook. and State of Illi the systemwill notwork perfectly. The sig 1 no1s,'have invented a certain new and useful nals being designed to operate on slight mar- Improvement in Supervisory Signals for Telegins of currentare to this extent uncertain. phone-Switchboards, of which the following It theobject of my present invention to p is av full, clear, concise, and exact description. provide an automatic signaling system which Y My invention relates to electrical signal dewilljbe as, simple as the one just described and vices and circuits therefor, and is intended more certain in its operation. I provide a more particularly to be used in connection local circuit containing a line-signal and conwith telephone-exchange systems for auto-- trolled by a switch which may be the line-rematically indicating to the central-oflice oplayofthe subscribers line, and the second sig- .65 erator a call from a'subscriber for connection nal-the supervisory s'ignalis included lIl' and also a subsequent call from the same suba branch circuit-which is adapted to beclosed scriber for disconnection. in a shunt of-the first-mentioi1ed signal'by a 'In' a well-known automatic signal system switch which may be closed in making confor telephone-exchanges the line-relay of a nection with the line, as in registering consubscribers line which is responsive to the I tacts of the plugand spring-jack. A resistfiow of current in the line controlled by the time is included in the undivided portion of subscribers telephone-switch controls a local the circuit, and a switch-contact, which may circuit containin a source of current, a linebe the 'back contact of the subscribers line-' signal lamp, an a resistance.- When the relay, is arranged to shunt'or short-circuit subscriber takes his telephone from its hook, thisresistance when-the-path containing the as" in initiatinga call, this local circuit is line-signal is opened. The supervisory sigclosed, and when he replaces his telephone nal is of considerably lower resistance than the line-relay allows its armature to fall back the line-signal, so that when both the parand open the local circuit. Asecond lamp allel paths areclosed the line-signal will be thesupervisorysi nal-isincluded inashuntshunted by, the superviso'ry'signal; but in circuit about the inc-lamp, said shunt being such a cas'e'the supervisory signal will not be 4 established in registering contacts of the plugexcited, because of the resistance in the cirand spring-jack switch by which the opera cuit. The line-signal,- however, unless it is tor makes temporary connection with the shunted b the low-resistance supervisory line. VVhen' the subscriber first takes his signal is a apted to be excited even with the telephone from its hook, the local circuit conresistance in the circuit. When the parallel tainingthe line-lamp is closed. Then when paths. containing the line and supervisory the operator answers. the call by plugging signals are both closed, neither signal will be into the spring-jack of the line whose'lamp is excited; but when the branch containing the thus lighted the supervisory lamp is brought line-signal is opened the switch which shortintoa shunt of the line-lamp, and each lamp circuits the resistance is also actuated and shunts the other, so that the illumination of the supervisorysignal will receive sufficient the line-lamp ceases and the supervisory lamp current for its excitation. remainsdark. Thenat the end of the con- I will describe my invention in connecversation when the subscriber replaces his tion w1th the accompanying drawing, which telephone" on its hook the line-relay allows its illustrates diagrammatically two telephone;

. armature to fall back and opens the path con.- lines'extendingfrom substations to a central taining the line .-lamp, thus. removing the office and a pair of lugs and their plug-cir shunt about the supervisory lamp, whereby cuitat the central o co for igniting. lines, the ace sufiicient current flows through the latterto system being organized-and equipped for aucause its illumination. This system just dotomatic's'ignalingin accordaneejwith myinscribed requires careful proportioning-of the vention. I i v r resistances and of the source of current. v Each telephoneline extends in twolimbs tral battery I).

1 2 from the usual substation apparatus to the contacts a a, respectively, of the several multiple spring-jacks a of the line at the central ofiice, and thence through the windings of the line-relay c to the poles of the con- The apparatus at the substation comprises theusual telephone receiver and transmitter in a bridge of the line controlled by a gravity telephone-switch (1, this switchbeing of the ordinary type adapted to close the circuit when the telephone-receiver is taken from the hook for use. .The usual call-bell isshownincluded with a condenser in a bridge of the line at each substation.

The spring-i acks at the central office have the short and :ong line springs a, 0, which are "connected; respectively, with the limbs 1 2 the" telephone-line, and said sprin Y'acks [are also'providedwith the usual thim es or testerings 'a' l All'the test-rings a of each line are connected together by a conductor .3, which extends to earth through two re-.

' sistan'cese and f. The resistance 6 may be seventy-five ohms and the resistance f may be" forty ohms. Alline-signal lamp'of comp'ara tively high resistancesay one hundred and forty ohmsis provided for each line in a local circuit from the battery I), said local circuit being made up of a conductor/1, ex I ole of the batterytending from the free through the line-signal amp andthe normally open switch-contacts o the line-relay c to the conductor 3 between the spring-'acks and the resistance 0. v l excited, therefore, the circuit of the battery I) is completed through the lamp 9 and resistances efand f in series to earth.

contact 0, W ich is connected to short-circuit the resistance e when the armature of the relay is in its retracted position. In other words, when the armature of the line-relayis retracted it breaks the shunt containing the line-signal lamp g at its front contact and establishes at its back contact a short circuit of resistance e. a

' I have shown the usual pair of plugs united by the cord conductors of a. plug-circuit,

whereby any two lines may be connected toplug. Each plug has t e usual tip, ring, and

sleeve contact pieces, which are adapted to engage with the short and long line-springs and the test-ring, respectively, of any ack into which such plug may be inserted. The

tips h k of the plugs are united. by the tipstrand 5 of the plu' circuit, and the ringcontacts k 7c are similarly united by the mug-strand 6. Thebattery b is shown connected ina bridge of the plug-circuit con- When the line-re ayis series. T-he line relay is also rovided with a normally resting ductors 5 fi'between the windingsoi a repeatin coil in the usual manner.

While I have for clearness shown in the drawing three batteries each marked 1), it will be understoodthat. in accordance with the Well-known practice a single central battery may be-employed, connectedas indicated.

Supervisory signal= lamps l m of, say, thirty-seven ohms resistancelare associated with the answering and calling plugs h and k, respectively, said lamps being included in conductors 7 8, respectively, which extend from the free pole of the battery I) to the third contacts h k respectively, of theplugs.

Itis understood, of course, that each plugcircuit may be provided with the usual ringing and listening keys with their associated apparatus, by which the o erator can communicate with any subscri er whose line is connected to the plugcircuitand may send signalin -current over such subscribers line to ring t e call-bell at the substation;

The operation of the automatic, signals is as follows: When the subscriber desiring a connection with another subscriber removes his telephone-receiver from its hook, his telephone-switch d automatically closes a bridge of the line containing his, telephone a paratus, and thus completes the circuit 0 the central-office battery 6 through his line-relay 0. The line-relay being excitedrby the current draws up its armature and closes. the local circuit 4 3, which contains the line-signal lamp 9 and the tworesistancese and f in The signal-lam .g is adapted to be lighted b the currentv owing in t is circuit, and its i luminationconstitutes a. signalto the operator to make connection with the corresponding line.- This she does by inserting her answering-plug h in the-answering springack, and by depressing her listening-ke is rought into communication wlth the su scriber'and asks him the number ofthe line with which he desires to be connected,[ Having received this information, she inserts the other plug 7c ofthe pair into the spring-rjack of the line wanted and sends the call-signal by'means of her ringing-key in the usual manner. The insertion of the answering-plug line brings the low-resistance supervisory lamp Z into shunt of the line-signal lamp g, so that the line-lamp is shunted out. The supervisory lamp, moreover, is not lighted, because resistances e and f in the circuit cut down the current below the amount required for its illumination. When, however; the armature ofthe line-relay is retracted, the shunt containing the supervisory lamp being closed at the plug and spring jack switch, as

after the conversat on has been finished and h'into the spring-jack of the calling I the resistance r will be short-circuited at the back contact: c of the line-relay. 'lncrcase l current will thus flow from th e battery I) through the supervisory lamp to the plug and spring-jack switch, through the conductor 3 and resistance f to earth, the resistance 6 being short-circuited, lamp will be lighted and indicate to the ope1"- ator a signal for discoi'inection. When the calling-plug is inserted in the jack of the called line, the supervisory lamp associated with such plug will of course be lighted until the called party responds, whereupon the line-relay switch will operate to interpose the resistance 6 in the circuit and cut down the current, so that the lamp will be darkened, and will remain dark until the'called party hangs up his telephone after the conversation has been finished Having thus (lGSOIlU-Gd my invention, I claim as new and desire to secure by Letters Patent the following: g

l The combination with a source of current, of a local circuit having two parallel branches with a signal device in each branch, means for opening and closing each branch, a resistance in the nndividedportion of the circuit and an electromagnetic switch controlling a shunt or short circuit of the resistance, the source of current, signal devices and resistance being proportioned to prevent the actuation of either signal device when both of said parallel branches are closed, one of said signal devices being adapted to beactuated by the increased current when the resistance is shunted. by the switch, substantially as described. v

2. The combination with a source of current, of a'signal device and a resistance in a local circuit therewith, a shunt of said signal device containing a second signal device, a

switch controlling said shunt, and a switch controlling the first-mentioned circuit adapted to cut out the first-mentioned signal device and shunt orshort-circuit the resistance, whereby said second signal devicereceives increased current for its operation.

The combination with atelephone-line extending from a substation to a central cffice, of a source of current and a substation telephone-switchcontrolling the flow of cur-.

rent in the line, a line-relay responsive to the current so controlled, a line-signal ofcome,

paratively highresistance included with resistances e and f in a local circuit controlled normally open contactsof the relay, a

spring-jack for the lint, a plug and plug-circuit for making connection therewith, a supervisory signal associated with the plugcircuit in a local shunt 'oi" the line-signal, adapted to be established in registering contacts of the plug and jack, the supervisory signal being of comparatively low resistance to shunt the line-signal and being adjusted or adapted to remain inert under the influence so that the-supervisory a local circuit therewith, a switch adapted to complete said local circuit, a switch a controlling a shunt or short circuit of the resist ance e, the completion of said shunt or short circuit being adapted to bring about the. ac

'tuation of the signal device, I, and a second signal device 9 controlled jointly by the switch and. the first1nentioned switch.

5. In a telephone-exchange system, the combination with a telephonedine extending from a. subscribers station to anexchange and terminating thereat in a line-jack, of cord-connecting apparatus for uniting this telephone-line with another for conversation,

a relay at the exchange operable from the substation, line and clearing-out lamps, par allel conductors including the lamps, a source of current for the linerelay and for the lamps, a resistance interposed betweenthe parallel conductors containing the lamps and their source of current, means whereby the cord-circuit will complete the parallel branch containing the clearingout lamp when connection is being established with the line, the armature of the relay serving to close the parallel branch containing the linelamp when attracted, a'nd a shunt closed by the armature of the relay when unattraoted about a part of the resistance, substantially as described.-v

.6. In a telephone '-exchange system, the combination with a telephone-line extending from a subscribers station to an exchange and terminating thereat in a linejack, of

cord connecting apparatus for uniting this telephone with another for conversation, a relay at the exchange operable from the substation, line and clearing out lamps, parallel conductors including the lamps, a source of currentfor the line-relay and for the lamps,

a resistance interposed between the parallel conductors containing the lamps and their source of current, means whereby the cordcircuit will complete the parallel branch containing the clearin -out lamp when connection is-being established with the line, the armature of the relay serving to close the parallel branch containing the line-lamp when attracted, and means controlled by the armature when unattracted for cutting out a portion of the resistance in circuit with the clearing-out lamp, the clearing-out lamp requiring more current for its operation than the line-lamp, circuit being established through the clearing-out lamp by theengagement of contacts associated with the gaged jack, substantially as described.

7. In a telephone central-exchange system,

plug and en associated with said local circuit togovern the strength of current therein and thereby to determine the display or non-display of 1 said signal; and a short circuit or shunt round said resistance device leading through the back armature contacts of said line-relay, and adapted to be closed whensaid relay is, unexcited, and opened when the same is excited, whereby the display of said supervisory signal is madedependent upon the attraction or retraction of the armature of said linerelay; substantially as set forth.

8. A telephone system comprising a sub scribers' line, a source of current connected with the line, a line-relay, a line-signal adapted to be brought into operation by the energization of said relay, a plug-switch, a supervisory lamp connected and arranged to shunt v out the said line-signal when the plug-switch is closed,'.and a shunt controlled by said relay and arrangedto reduce the resistance of the supervisory lam circuit when the lire-circuit is open and t 1e plug-switch closed.

9. A telephone systemcomprising' a subscr'ibers line, a substation-switch for closing the line-circuit,a source of current supply connected with the line, a relay connected with the line, a line signal associated with said relay and controlled thereby, a plugswitch and a supervisory signal connected and arranged for shunting out said line-sig nal when the line-circuit is closed, and a normally closed shunt controlled by said relay and adapted for reducing the resistance of the supervisory signal circuit, said shunt closing when the line-circuit is opened by the substation-switch. I

10. The combination of a normally open signal circuit, a normally closed shunt in said circuit, means in said circuit for supplying current, a normally open line-circuit-ineluding said source of current, and a relay included in said line-circuit and adapted when energized to open said shunt when the signalcircuit is closed, so as to prevent the display of said signal, said relay when dee'nergized being adapted to close said shunt, so as to causethe displayof said signal.

11. The combination of a subscribers line,

a subscribers switch, a line-relay, a suitable source of current for supplyirg current to the life through said relay,-a normally open circuit includingv said source of current, a supervisory signal in said open circuit, a suitable resistance in said circuit, and a normally closed shuntin said normally open circuit extending around said resistance, said shunt being controlled by said line-relay, whereby the closing of said subscribers switch opens said shunt, so as to prevent the display of said supervisory si nal when the normally open. circuit is close and whereby the opening of said subscribers switch operates to close said shunt, so as'to cause a display of said supervisory signal when the said nor- -mally open circuit is closed.

In witness whereof I hereunto subscribe my name this 28th day of December, A. D.

' FRANK R. MGBERTY. Witnesses:

GEORGE P. BARTON EDWIN H. SMYTHE. 

